(a) Field of the Invention
The present invention relates to an apparatus and method of estimating a signal-to-noise ratio (SNR), and more particularly, to an apparatus and method of estimating a signal-to-noise ratio (SNR) of a received signal when the received signal has a timing offset in an OFDM system.
(b) Description of the Related Art
In order to estimate a signal-to-noise ratio (SNR) of a received signal, it is important to calculate accurate noise power. However, if a timing offset exists in the received signal, a phase rotation occurs in a frequency domain, which deteriorates the estimation performance of a signal-to-noise ratio (SNR).
As a technology according to the related art for removing a phase rotation component and estimating a signal-to-noise ratio (SNR), there is a method in which a received signal whose phase rotation component is removed is restored using a time synchronization error calculator and a phase rotation compensator. This method performs a fast Fourier transform (FFT) on a preamble symbol of a received signal, compares the converted signal with a preamble symbol generated by a receiver to calculate a signal-to-noise ratio (SNR), estimates an accurate time error with respect to the received signal having a time error using the time synchronization error calculator and the phase rotation compensator, and restores the phase rotated received signal on the basis of estimated time error information. In this way, an accurate time error can be estimated without installing separate hardware, and a phase error that has occurred is restored on the basis of estimated time error information to calculate an accurate signal-to-noise ratio (SNR). However, this method has a problem in that it is required to detect an accurate time synchronization error, provide a complex multiplier to remove a phase rotation component, and store a value of the phase rotation component.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.